1. Field of the Invention
The present invention relates generally to a device for use in the construction of dental prostheses. More particularly, the present invention relates to a facial registration tool, which simulates the appearance of upper anterior teeth, and a means for attaching the registration tool to a wax rim. The facial registration tool of the present invention is used to record the desired position and orientation of artificial teeth, as the teeth are to appear in a finished dental prosthesis.
2. Description of the Related Art
One of the principle difficulties involved in the construction of dental prostheses is the positioning and placement of artificial teeth. Proper alignment of the upper anterior teeth affects aesthetics, phonetics and function for denture wearers. Ridge resorption, and in particular, the way in which the maxillary arch recedes up and back to an unpredictable extent after tooth extraction, can alter the way a person looks, speaks, and otherwise functions with dentures. It is widely recognized that aesthetics is a prominent concern of a dental patient who is to receive a prosthesis. As the upper anterior teeth are the most visible teeth, and since the position of the upper anterior teeth often dictates the position of the other teeth to be replaced by the prosthesis, the proper placement of the upper anterior teeth in the prosthesis is critical to the patient""s ultimate satisfaction. The challenge of proper tooth placement is further complicated by ridge resorption as the artificial teeth cannot simply be placed over the ridge as they would appear in a natural ridge structure before tooth removal.
In the usual practice of dental prostheses construction, impressions of the patient""s mouth are taken during a first appointment, and gypsum models are made from the impressions. These models are used, in turn, by the dental laboratory to prepare a wax bite rim. Typically, the dentist will take a bite registration at the second patient appointment using the bite rim, and at the third appointment the dentist will try an arrangement of the artificial teeth in wax for proper fit and appearance in the patient""s mouth.
Miscommunication between dentist and dental laboratory and other errors often occur during this process. The dentist has access to the patient, but does not construct the prosthesis, while the laboratory that constructs the prosthesis is generally without access to the patient. At the second appointment, the dentist usually has only a rim of wax attached to a preformed base, which has been adapted to fit the patient""s gum tissue. This is commonly referred to as a bite rim, and this step in the process is often referred to as the wax rim fitting.
The standard practice of wax rim fitting requires the dentist to scribe a line in the upper wax rim to indicate where the middle of the two upper central incisors should be, and to shape and carve the wax rim in various areas to indicate the desired length and depth of the upper anterior teeth. Because of the time that it takes to do this shaping and carving, and as dentists presently do not have a useful tool to provide a perspective of how the patient will look with teeth, this important step of prosthesis construction is often done poorly, incompletely, or not at all. Even when the wax rim is carefully shaped and carved by the dentist, the desired position of the artificial teeth are difficult for patient and dentist to see because of the uniformity of color and material between teeth carved of wax and gums of the same wax. As described above, the teeth cannot be placed solely based upon the patient""s ridge impression because of the resorption that occurs after tooth removal.
Having made some indication of the desired position for the artificial teeth, the arrangement of the denture teeth is completed by the dental laboratory, generally in a setting apart from the clinic in which the dentist examines the patient and fits the prosthesis. The art of prosthetic construction is both a time consuming and creatively challenging task. This task is further complicated when tooth-placement information from dentist-patient interaction is incomplete or vague, as the dental technician does not have access to the patient for fitting information. If the initial placement of artificial teeth is not to the satisfaction of the patient or dentist, the teeth must be reset, requiring the patient to return for another appointment. Dentist, laboratory, and patient incur additional time and costs as the result of this deficiency in dentist-laboratory practice.
As tooth placement is a critical part of prosthetic dentistry, the present invention will improve the placement and construction of artificial teeth by allowing dentist and patient to visualize the appearance of the finished denture while still at the wax rim fitting stage, and to effectively communicate the resulting tooth-placement information to the dental laboratory for use in construction of the finished prosthesis.
Accordingly, one object of the present invention is to provide a facial registration tool for use in dentistry, which can be used on any patient needing a removable prosthesis that replaces some or all of the upper anterior teeth.
Another object of the present invention is to provide a simple and effective means for dentist and patient to record information with respect to the desired position and orientation of the upper anterior teeth for communication to the dental laboratory prior to the setting of the artificial teeth.
Another object of the present invention is to provide a means for recording details such as patient midline, incisal edge position, occlusal plane, facial contour, high lip line, overjet, overbite, or angle of inclination in relation to the desired position of the anterior teeth.
A related object of the present invention is to improve the efficiency of prosthetic dentistry by eliminating rework that frequently results from miscommunication of information between dentist and dental laboratory.
Another related object of the present invention is to allow dentist and patient to position, and reposition, the tool quickly to try different positions and orientations of the anterior teeth before selecting a particular position and orientation for prosthetic construction.
The present invention relates to a facial registration tool, which simulates the appearance of upper anterior teeth, and a means for attaching the registration tool to a wax rim. The facial registration tool of the present invention may be used to record the desired position and orientation of artificial teeth, as the teeth are to appear in a finished dental prosthesis.
These and other advantages will be apparent from the following description.
According to one aspect of the preferred invention, a facial registration tool for use in the fabrication of dental prostheses includes a simple one-piece manufacture that simulates the appearance of natural teeth when used with a wax bite rim. One embodiment of the invention includes four interconnected artificial teeth and a retention node extending posteriorly from the artificial teeth for attaching the tool to a wax bite rim. When attached to a bite rim, the facial registration tool simulates the natural appearance of upper incisors as the teeth would appear in a patient""s mouth, and may be used accordingly to find the optimal placement and orientation desired for the teeth in the final prosthesis, and as a simple and effective means to record and transmit this information to the dental laboratory responsible for prosthesis construction. Another aspect of the present invention simulates the appearance of the left and right cuspids as well as the central and lateral incisors of the patient. Various retention means for attaching the tool to a wax bite rim are also taught.
The facial registration tool as taught in the present invention provides a number of advantages. The simple and inexpensive tool of the present invention can be used in virtually any situation where a removable prosthesis is to be fabricated, and the upper anterior teeth are missing. It gives the dentist and patient the ability to see teeth, instead of just a wax rim, when recording the desired position of the artificial teeth as they should appear in the finished prosthesis. This in turn allows the dental technician responsible for prosthesis construction to be certain of where to set the artificial teeth for the try-in appointment. By eliminating the uncertainty in tooth placement, which is so common in the art of dental prosthetic construction today, the present invention can be used to eliminate resets and additional patient appointments, both of which cost dentist and laboratory time and money, and unnecessarily inconvenience the patient.